Chapter 11.2
Relate the concept of the gene to the sequence of nucleotides in DNA Sequence the steps involved in protein synthesis ◦ DNA mRNA = “transcription” ◦ mRNA protein = “translation”
The sequences of nucleotides in DNA contain information that code for production of proteins These proteins fold into 3-d shapes that have different functions in key processes ◦ Usually ENZYMES Used in active transport, ATP-ADP cycle, etc. Proteins are polymers of amino acids ◦ A.P.E.
Single stranded Sugar is “ribose” RNA has “U” rather than “T” in its code ◦ RNA’s nitrogen bases are: AA UU CC GG RNA molecules are “workers” of protein synthesis
There are 3 types of RNA molecules ◦ mRNA (messenger RNA) ◦ rRNA (ribosomal RNA) ◦ tRNA (transfer RNA)
Transcription is moving from DNA to a single mRNA strand ◦ Occurs in the nucleus of a cell ◦ mRNA carries genetic information through nuclear envelope to the ribosomes in the cytoplasm for protein synthesis
Introns: non-coding portions of DNA Exons: coding portions of DNA Both are copied from DNA to mRNA, but one is removed before piecing together the protein from mRNA
Based off sequence of nucleotides Proteins contain chains of amino acids There are 20 common amino acids Group of 3 nitrogen bases (AAA) is called a codon 64 different possible codons ◦ Table 11.1 pg. 92 More than 1 codon = same amino acid 1 codon can only be 1 amino acid ◦ With exception of AUG = start, methionine codon
The genetic code is UNIVERSAL ◦ Because all organisms use the same genetic code, thus meaning we must all have a common origin
Moving from mRNA to protein Translation: process of converting information in a sequence of nitrogen bases in mRNA into a sequence of amino acids (protein) Takes place in the cytoplasm wherever ribosomes are Amino acids are held together by PEPTIDE BONDS
A. The Role of Transfer RNA (tRNA) ◦ Attaches to only 1 type of amino acid ◦ Has the “ANTICODON” for the mRNA codon B. Translating the mRNA code ◦ Start and stop codons ◦ Ribosomes (rRNA) slide down the mRNA molecule and signal to bring in the correct tRNA molecule with the correct amino acid for forming a protein ◦ tRNA releases protein and goes back to pick up another free floating amino acid
B. Translating the mRNA code ◦ Ribosome continues to slide down mRNA to next codon sequence, etc, etc etc ◦ Proteins fold into 3-d shapes to become enzymes and cell structures
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